SciELO - Scientific Electronic Library Online

 
vol.34 número2 índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Articulo

Indicadores

    Links relacionados

    • En proceso de indezaciónCitado por Google
    • En proceso de indezaciónSimilares en Google

    Compartir


    Water SA

    versión On-line ISSN 1816-7950
    versión impresa ISSN 0378-4738

    Water SA vol.34 no.2 Pretoria feb. 2008

     

    Batch and automated SVI measurements based on short-term temperature variations

     

     

    WH RössleI; WA PretoriusII

    IERWAT Chair in Wastewater Management, Department of Chemical Engineering (Water Utilisation Division), University of Pretoria, Pretoria 0001, South Africa
    IIPretWatSpes, Ysterhoutlaan 59, Val de Grace 0184, South Africa

    Correspondence

     

     


    ABSTRACT

    Effects of short-term temperature variations on the sludge volume index (SVI) are evaluated with batch and automated mixed liquor suspended solids (MLSS) settling tests. The test-cylinder environment and meteorological conditions have a direct influence on the MLSS sample temperature (Ts). A T change of 4.3°C over the 30 min settling test duration results in an inverse SVI change of 63.0 m/g, at an average SVI decrease of 14.8 m/g per 1°C T increase. T compensation or control during routine SVI tests is not common practice, partially due to a lack of temperature-controlled equipment and an absence of Ts-based MLSS settling models. A practical solution is found to reduce Ts variations experienced before and during batch MLSS settling tests. An automated MLSS settling meter is used to demonstrate a semi-continuous on-line method to determine SVI at the operational reactor temperature (T) of a full-scale plant. Basic and best-fit SVI models are obtained from the SVI data generated over diurnal periods, based on MLSS concentration and T fluctuations. These SVI models confirm the inverse dependence of SVI on temperature for the site-specific conditions. A diurnal T fluctuation of 1.8°C results in an SVI change of 26.6 m/g, at an average -14.8 m/g SVI change per 1°C Tr variation.

    Keywords: activated sludge, mixed liquor suspended solids (MLSS), model, sludge volume index (SVI), settleability, temperature, wastewater


     

    "Full text available in PDF"

     

    References

    BYE CM and DoLD PL (1998) Sludge volume index settleability measures: effect of solids characteristics and test parameters. Water Environ. Res. 70 (1) 87-93.         [ Links ]

    CATUNDA PFC and VAN HAANDEL AC (1992) Activated sludge settling. Part I: Experimental determination of activated sludge settle-ability. Water SA 18(3) 165-172.         [ Links ]

    ÇETIN FD and SÚRÚCÚ G (1990) Effects of temperature and pH on the settleability of activated sludge flocs. Water Sci. Technol. 22(9) 249-254.         [ Links ]

    CLEMENTS MS (1976) The application of static column tests to sedimentation tank design. Water Pollut. Control 75 (3) 360-376.         [ Links ]

    DAIGGER GT and ROPER RE (Jr.) (1985) The relationship between SVI and activated sludge settling characteristics. J. Water Pollut. Control Fed. 57(8) 859-866.         [ Links ]

    DAIGGER GT (1995) Development of refined clarifier operating diagrams using an updated settling characteristics database. Water Environ. Res. 67 (1) 95-100.         [ Links ]

    DATAFIT (2005) Oakdale Engineering, Statistical Software Package, Version 8.1.69, Evaluation Copy, US. http://www.curvefitting.com. (Accessed on 15/01/2005).         [ Links ]

    DICK RI and VESILIND PA (1969) The Sludge Volume Index - What is it? J. Water Pollut. Control Fed. 41(7) 1285-1291.         [ Links ]

    EKAMA GA and MARAIS GVR (1984) Two improved activated sludge settleability parameters. IMESA 6(9) 20-26.         [ Links ]

    EKAMA GA, BARNARD JL, GÚNTHERT FW, KREBS P, McCoRQUODALE JA, PARKER DS and WAHLBERG EJ (1997) Secondary Settling Tanks: Theory, Modelling, Design and Operation. IAWQ Scientific and Technical Report No. 6. IWA Publishing, Simpson Drewett and Co. Ltd., Richmond, Surrey, England.         [ Links ]

    GERARDI MH (2002) Settleability Problems and Loss of Solids in the Activated Sludge Process. John Wiley & Sons, Hoboken, New Jersey, USA.         [ Links ]

    GERNAEY K, VANDERHASSELT A, BOGAERT H, VANROLLEGHEM P and VERSTRAETE W (1998) Sensors to monitor biological nitrogen removal and activated sludge settling. J. Microbiol. Methods 32 193-204.         [ Links ]

    GILLOT S and VANROLLEGHEM PA (2003) Equilibrium temperature in aerated basins-comparison of two prediction models. Water Res. 37 3742-3748.         [ Links ]

    GRADY CPL (Jr.) and FILIPE CDM (2000) Ecological engineering of bioreactors for wastewater treatment. Water Air Soil Pollut. 123 117-132.         [ Links ]

    HÄRTEL L and PÖPEL HJ (1992) A dynamic secondary clarifier model including processes of sludge thickening. Water Sci. Technol. 25 (6) 267-284.         [ Links ]

    JIN B, WILÉN BM and LANT P (2003) A comprehensive insight into floc characteristics and their impact on compressibility and settleability of activated sludge. Chem. Eng. J. 95 (1-3) 221-234.         [ Links ]

    KRISHNA C and VAN LooSDRECHT MCM (1999) Effect of temperature on storage polymers and settleability of activated sludge. Water Res. 33 (10) 2374-2382.         [ Links ]

    MAKINIA J, WELLS SA and ZIMA P (2005) Temperature modeling in activated sludge systems: A case study. Water Environ. Res. 77 (5) 197-204.         [ Links ]

    MINES RO and HORN CR (2004) Misconceptions about unstirred SVI. Proc. 2004 World Water and Environmental Resources Congress. 27 June - 1 July, Salt Lake City, USA.         [ Links ]

    MORGAN-SAGASTUME F and ALLEN DG (2003) Effects of temperature transient conditions on aerobic biological treatment of waste-water. Water Res. 37(15) 3590-3601.         [ Links ]

    PARKER DS, WAHLBERG EJ and GERGES HZ (2000) Improving secondary clarifier performance and capacity using a structured diagnostic approach. Water Sci. Technol. 41 (9) 201-208.         [ Links ]

    SCHERFIG J, SCHLEISNER L, BR0ND S and KILDE N (1996) Dynamic temperature changes in wastewater treatment plants. Water Environ. Res. 68 (2) 143-151.         [ Links ]

    SEKINE T, TSUGURA H, URUSHIBARA S, FURUYA N, FUJIMOTO E and MATSUI S (1989) Evaluation of settleability of activated sludge using a sludge settling analyser. Water Res. 23 (3) 361-367.         [ Links ]

    SEZGIN M (1982) Variation of sludge volume index with activated sludge characteristics. Water Res. 16 83-88.         [ Links ]

    SIMON J, WIESE J and STEINMETZ H (2005) Results of field tests and possible applications for in-situ sludge volume probes. Proc. 2nd IWA-ICA Conference. 29 May - 2 June, Busan, South Korea.         [ Links ]

    STANDARD METHoDS (1998) Standard Methods for the Examination of Water and Wastewater (20th edn.) American Public Health Association (APHA)/American Water Works Association (AWWA)/ Water Environment Federation (WEF), Washington, D.C., USA.         [ Links ]

    TANDoI V, JENKINS D and WANNER J (2006) Activated Sludge Separation Problems: Theory, Control Measures, Practical Experience. IWA Scientific and Technical Report No. 16, IWA Publishing, London, England.         [ Links ]

    VANDERHASSELT A, ASPEGREN H, VANROLLEGHEM P and VERSTRAETE W (1999) Settling characterisation using on-line sensors at a full-scale wastewater treatment plant. Water SA 25 (4) 453-458.         [ Links ]

    VANROLLEGHEM PA, CLERCQ BD, CLERCQ JD, DEVISSCHER M, KINNEAR DJ and NOPENS I (2006) New measurement techniques for secondary settlers: A review. Water Sci. Technol. 53 (4-5) 419-429.         [ Links ]

    WILÉN BM (1999) Properties of Activated Sludge Flocs. Paper VI. Effect of Temperature and Cold-Storage on Activated Sludge Floc Strength. Ph.D. Thesis, Dissertation No 15, Department of Sanitary Engineering, Chalmers University of Technology, Göteborg, Sweden.         [ Links ]

    WILÉN BM, ONUKI M, HERMANSSON M, LUMLEY D and MINO T (2006) Influence of flocculation and settling properties of activated sludge in relation to secondary settler performance. Water Sci. Technol. 54(1) 147-155.         [ Links ]

    ZHANG S, YANG F, LIU Y, ZHANG X, YAMADA Y and FURUKAWA K (2006) Performance of a metallic membrane bioreactor treating simulated distillery wastewater at temperatures of 30 to 45°C. Desalination 194146-155.         [ Links ]

     

     

    Correspondence:
    ERWAT, PO Box 13106, Norkem Park, 1631
    +27 11 929-7000; Fax: +27 11 929-7105
    E-mail: wernerr@erwat.co.za

    Received 9 November 2007
    Accepted in revised form 12 March 2008